Passage Summary: People buying items on sale without a list somehow spent more money than people buying full-price items with a list, even though they walked out with the same amount of stuff.

Reasoning: Shoppers without lists who bought items at half-price or less ended up spending more total money for the same number of items than shoppers who used lists and paid full price.

Analysis: The paradox here is a price-per-item discrepancy. How can 'half-price' items result in a higher total bill than 'full-price' items for the same quantity? To resolve this, we need an explanation for why the discounted items were still more expensive than the non-discounted ones. Perhaps the bargain hunters were buying high-end luxury goods that are expensive even at 50% off, while the list-shoppers were buying budget-friendly staples. Look for an answer that addresses the inherent value or base cost of the items chosen by each group.